Crossbar switch with resilient last motion connection between row co-ordinate and interposer members

ABSTRACT

A crossbar switch in which a row of interposer blocks are positioned under contact operating combs by a select bar and then one of the interposer blocks is driven to operate its comb by a bridge mechanism common to a column of interposer blocks. Each interposer block is mounted on a rigid arm which pivots under the action of a select bar. The pivot end of the arm is maintained only by a leaf spring so that if the interposer end is obstructed on pivoting, either by a design stop or by a comb if the bridge has first been operated, then distortion or overstressing is avoided by disengaging of the arm pivot.

United States Patent 1 Whitehead Oct. 9, 1973 [75] Inventor: Paul Timothy Whitehead, Coventry,

England [73] Assignee: The General Electric Company Limited, London, England 22 Filed: Sept. 7, 1972 [21] Appl. No.: 287,051

[30] Foreign Application Priority Data Sept. 8, 1971 Great Britain 41,917/71 [52] US. Cl 200/175, ZOO/153 V, 335/112 [51] Int. Cl. H01h 67/26, HOlh 3/48 [58] Field of Search ZOO/175, 176, 177,

2,740,843 4/1956 Montchausse 200/177 3,500,004 3/1970 Kershner et a1. 200/175 3,631,523 12/1971 Feetenby ZOO/175 Primary Examiner-J. V. Truhe Assistant ExaminerRobert A. Vanderhye Attorney-Morris Kirschstein et a1.

[5 7] ABSTRACT A crossbar switch in which a row of interposer blocks are positioned under contact operating combs by a select bar and then one of the interposer blocks is driven to operate its comb by a bridge mechanism common to a column of interposer blocks. Each interposer block is mounted on a rigid arm which pivots under the action of a select bar. The pivot end of the arm is maintained only by a leaf spring so that if the interposer end is obstructed on pivoting, either by a design stop or by a comb if the bridge has first been operated, then distortion or overstressing is avoided by dis- [56] kgferences Cited engaging of the arm pivot.

UNITED STATES PATENTS 2,704,937 3/1955 Stokes 200/153 V UX 6 Claims, 3 Drawing Figures PATENTED BET 9 I975 SHEET 10F 3 PATENTED 91973 SHEET 2 [1F 3 PATENTEuam ems SHEET 3 OF 3 Fig.3

This invention relates to electric switches and particularly to crossbar switches such as may be used in telephone exchanges.

Examples of crossbar switches are described in the complete specifications of US. Pat. Nos. 3,631,522-3, 3,617,961 and 3,622,924 and application Ser. No. 33,615 and the present invention is directed to an improvement in such switches.

For the purposes of this specification a crossbar switch is defined as a switch having a plurality of conducting paths in each of two coordinate directions, a path in one of the two directions being connected to a path in the other direction by a contact set at the crosspoint of the two paths, and each contact set being operated by co-operation of a coordinate member in respect of one of the two paths and a coordinate member in respect of the other. Thus the term crossbar switch is not to be taken as limiting the kind of contact set employed which may for example be relay contact sets or wire multiples suchas will be described.

According to the present invention, a crossbar switch comprises an array of contact sets arranged in rows and columns, an interposer member and an elongated interposer arm in respect of each contact set, a set of row coordinate members each coupled to the interposer members of a respective row by way of the respective interposer arms, means for operating each row coordinate member individually to drive the associated row of interposer members in a direction transverse to the length of the respective interposer arms into respective driving positions, a set of column coordinate members each column coordinate member being coupled to the interposer members of a respective column, means for operating each column coordinate member individually to drive any interposer member of the respective column, which interposer member is in a said driving position, in a direction generally along the length of the respective interposer arm into operative engagement with the associated contact set, the interposer members being slidable along the respective interposer arms, and resilient support means for the interposer arms, said resilient support means providing lost motion coupling between a row co-ordinate member and the associated interposer members whereby the travel of said interposer members may be limited independently of the travel of the row co-ordinate members.

Each interposer arm is preferably substantially rigid and the associated interposer member is preferably coupled to the arm at or near one end thereof, the arm having a transverse pivot axis at or near the other end of the arm. The resilientsupport means for the interposer arms may comprise respective leaf springs which apply a spring bias to and serve to locate said arms. A row aoordinate member may engage the associated interposer arm at a point intermediate the interposer member and the pivot axis, the arrangement being such that if the movement of the interposer member is limited on operation of the row coordinate member the pivot axis is displaced against said spring bias.

Stop means may be provided in the region of the interposer member to limit the pivotal movement of the interposer arm about the pivot axis, and movement of the associated row coordinate member beyond an extent at which said stop means is engaged by said arm is preferably arranged to cause displacement of the pivot axis against said spring bias.

The arrangement is preferably such that in operation of a contact set the associated interposer member is first moved into a said driving position from which it can be driven to operate a contact-making comb mem-' ber by operation of the associated column coordinate member, the latter operation causing the other interposer members of the column to be driven into positions from which movement by respective row coordinate members, preparatory to the operation of a contact set in a different column, is obstructed by respective comb members, such obstruction being accommodated by the lost motion between the movement of a row coordinate member and the resulting movement of an interposer member.

A crossbar switch in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, of which:

FIG. 1 is an exploded front elevation of the crossbar switch, the upper part being the contact set assembly and the lower part the operating mechanism;

FIG. 2 is a diagrammatic perspective view of the contact set assembly showing a three-dimensional array of contacts; and

FIG. 3 is a part elevation of a bridge or column mechanism.

The contact set assembly 51, shown in the upper part of FIG. 1 is described in detail in the specification of US. Pat. Nos. 3,631,522-3 and application Ser. No. 33,615. It comprises twelve tiers of conductors, as shown in FIG. 2, each tier comprising -row conductors 2 and column conductors 3 arranged to constitute rows and columns. The row and column conductors are slightly spaced apart so that a connection between a selected row wire 2 and a selected column wire 3 can be made by deflecting the row wire 2 upwards (in the drawings) into contact with the column wire. As indicated in FIG. 1, the column wires, transverse to the plane of the drawing, are in fact duplicated in accordance with normal redundancy practice, the two contacts at the crosspoint of a row and a column being made simultaneously. The column conductors 3 are in the form of a hairpin" or elongated U-shape to provide this duplication.

Twelve such tiers are superimposed, the twelve contacts (each duplicated as described above) at each crosspoint constituting a contact set. The 12 contacts of each contact set are operated in unison by a comb 25, as shown in FIG. 1. The comb 25 has 12 cantilever teethwhich interleave the twelve tiers at the crosspoint. The back of the comb has a downward extension 32 which enters the operating mechanism 52 through a column slot in a plate 61.

If the comb extension 32 is driven upwards then the particular contact set is operated.

It is commonly necessary to have only four wires in a path so that the 12 contact pairs of a set can be used to increase the number of outlet paths available to a four-wire inlet path. In FIG. 2 three levels are shown, whereby a four-wire inlet path to a column is connected to the upper four, centre four, or lower four column conductors.

Three rows are allocated to this choice of level, the row conductors in these rows being only short terminal conductors 18. Thus to effect a connection through the switch between a four-wire input to a particular column and a four-wire outlet from a particular row at a particular level, two contact sets must be operated, one in the three level selecting rows and one in the main body of the row/column crosspoints.

Referring now to FIGS. 1 and 3, each column of the contact set has an associated bridge assembly 62 which is mounted as a complete assembly on the plate 61 by way of screws 63. The structure of the bridge assemblies shown in FIG. 1 is similar to the assemblies described in the above patent applications. Each bridge assembly comprises a square U-shaped magnetic core 65 lying in the plane of the column with the open end of the U facing up toward the contact set assembly. The left hand upper edges 81 of the core 65, as viewed in FIGS. 1 and 3 form pivots for an armature assembly, part of which is shown in FIG. 3. This assembly comprises a non-magnetic moulded frame 83 having pivot inserts (not shown) to engage the core 65. A magnetic armature 78 extending the length of the bridge assembly is clamped to the frame 83 which is such as to enable the armature 78 to pivot into a position of close engagement with the side face of the U shaped core to close the magnetic circuit. An energizing winding (not shown) is mounted on the lower part of the core 65 to form with the core an electromagnet for attracting the armature 78. The disengaged position of the armature assembly, as shown in FIGS. 1 and 3, is maintained, as shown in FIG. 3, by a coil spring 190. This is an alternative to the leaf spring 92 of the above applications.

Extending from the frame 83 at positions along the bridge assembly in between the rows are web portions 98. Formed in the sides of these web portions are guide channels 97 which carry interposer blocks 102, thirteen on each armature assembly, each block being carried between the guide channels 97 of adjacent webs 98.

The thirteen interposer blocks 102 are therefore carried with the armature assembly as it pivots on energization of the core winding. The position of the pivot edge 81 on the core in relation to that of the interposer blocks 102 is such that the latter rise almost vertically on energization of the electromagnet.

Each interposer block 102 is free to move in its respective guide channels 97 in a direction along the line of the particular row, subject to the position of an interposer arm 101 which extends through a notch in one side of the interposer block 102. The arm 101 is a fairly close sliding fit in the interposer block 102, at least in the row direction, so that the block 102 follows movement of the arm 101 in that direction.

Unlike the arrangements of the above mentioned patent applications each interposer arm 101 is a substantially rigid moulding having a forked lower end which bears against a mounting plate 86 and is separated from the lower end of the adjacent arm or arms by a web or webs 87 of the plate 86. A respective leaf spring 191, which is clamped at its lower end to the plate 86, extends upwards between the fork ends of each arm 101 and engages a wedge-shaped projection 192 on the arm 101. The leaf spring 191 is shaped at its upper end to embrace the projection sufficiently tightly to locate the arm 101 in the vertical direction.

The lower ends 193 of the arm 101 are rounded to provide a pivot axis, which does of course move very slightly with pivoting of the arm. The head 104 of the arm 101 extends beyond the interposer block 102 and into a channel 197 which similarly accommodates the heads 104 of all of the arms 101 of that column.

The head of the arm 101 is pressed to the rear wall of the channel 197 by the spring 191 as shown in FIG. 3. In this position the interposer block 102 is withdrawn towards the rear of the channel 97 and horizontally away from the lower extension 32 of the associated com 25. Operation of the bridge magnet to pivot the armature assembly would then cause no engagement of the comb extension 32.

In the alternative position of the arm 101 with the head 104 abutting the front wall of the channel 197 the interposer block 102 lies under the comb extension 32. Operation of the bridge magnet in this position causes the interposer block 102 to be thrust up against the comb extension to operate the associated contact set.

Excessive upward force on the comb may be prevented, as in the previous applications mentioned above, by the use of a lost motion coupling (not shown) between the web portions 98 and the frame 83 of the armature assembly.

Movement of the interposer arm 101 between the two positions above is achieved by a select bar 181. There is one such select bar for each row of contact sets. Each select bar 181 has ten notches, one for each interposer arm in the row. The select bars are operable by individual electromagnets (not shown) in an assembly 123 (FIG. 1). The other end is carried by a guide 124 and abuts against an off-normal contact comb 127 of an assembly 126. A return spring in the assembly 123 maintains the normal position of the select bar to the left and as shown in FIG. 3.

On operation of a select magnet all of the interposer arms 101 of a row will be driven to the right, pivoting about their lower ends 193 until their head ends 104 engage the front walls of the respective channels 197.

The leading edge of each notch in the select bar 181 is normally well clear of the respective interposer arm 101 to allow the select bar to return to its rest position while a particular interposer arm remains deflected in the operation of a contact set.

When a select bar is operated it may happen that, due to manufacturing tolerances etc. the travel of the select bar is incomplete when the head 104 of an interposer arm 101 engages the front wall of the channel 197. In this case the return force of the spring 191 is overcome by the driving force of the select bar 181 and the arm 101 pivots about the point of engagement of the head 104 with the front wall of the channel 197. The original pivot axis of the arm 101, through the end 193, is then displaced and the end 193 of the arm 101 is lifted off the plate 86.

By virtue of this lost motion between the select bar 181 and the interposer block 102 greater freedom is provided in the travel of the select bar while the travel of the interposer block is accurately limited.

In addition to this facility, available in normal operation of a single contact set, the following facility is provided.

Thus when a single contact set is to be operated, first the appropriate select bar is operated to drive all ten of the associated interposer blocks 102 under their respective combs, and then the appropriate bridge magnet is energised to drive the one comb common to both selected row and column. The select magnet is then released, leaving the selected interposer block 102 trapped between the comb (which has its own return spring incorporated) and the lower ledge of the guide channels 97, the selected bridge magnet being still energized. Following such operation of a particular contact set and during the time that it remains operated, all of the other interposer blocks 102 of the same column are held in an elevated position vertically beyond the extremities of the comb ends and horizontally withdrawn from them. If now, as may commonly occur in practice, a further contact set in a different column and in a different row is to be operated (the problem does not arise if the row is the same, and operation of a further contact set in the same column is not possible, as the first contact set would-drop out), then it will be seen that the interposer block 102 in the column already in use and in the row newly selected, will be driven against the side of the extension 32 of the associated comb.

This would be damaging if the spring biased mounting of the arm 101 did not allow the arm 101 to be driven by the select bar into pivotal motion about the point of abutment of the interposer block 102 and the comb extension 32.

The selection of the level to which a four wire inlet path is to be connected is carried out at the same time as the selection of the contact set interconnecting the appropriate column and row conductors. Thus one of the select bars of rows 1 to 3 (FIG. 2) is operated together with the select bar of that one of rows 4 to 13 which is associated with the required outlet, following which the operation of the appropriate column armature assembly will connect the four wire inlet to the column wires at the required level and thence to the required four wire outlet from the selected row at that level.

I claim:

1. A crossbar switch comprising an array of contact sets arranged in rows and columns, an interposer member and an elongated interposer arm in respect of each contact set, a set of row coordinate members each coupled to the interposer members of a respective row by way of the respective interposer arms, means for operating each row co-ordinate member individually to drive the associated row of interposer members in a direction transverse to the length of the respective interposer arms into respective driving positions, a set of column co-ordinate members each column co-ordinate member being coupled to the interposer members of a respective column, means for operating each column co-ordinate member individually to drive any interposer member of the respective column, which interposer member is in a said driving position, in a direction generally along the length of the respective interposer arm into operative engagement with the associated contact set, the interposer members being slidable along the respective interposer arms, and resilient support means for the interposer arms, said resilient support means providing lost motion coupling between a row co-ordinate member and the associated interposer members whereby the travel of said interposer members may be limited independently of the travel of the row co-ordinate members.

2. A crossbar switch in accordance with claim 1 wherein each interposer arm is substantially rigid and the associated interposer member is coupled to the arm at or near one end thereof, the arm having a transverse pivot axis at or near the other end of the arm.

3. A crossbar switch in accordance with claim 2 wherein said resilient support means for the interposer arms comprises respective leaf springs which apply a spring bias to and serve to locate said arms.

4. A crossbar switch in accordance with claim 2 wherein each row co-ordinate member engages the associated interposer arm at a point intermediate the interposer member and the pivot axis, the arrangement being such that if the movement of the interposer member is limited on operation of the row co-ordinate member the pivot axis is displaced against said spring bias.

5. A crossbar switch in accordance with claim 2 wherein stop means are provided in the region of the interposer member to limit the pivotal movement of the interposer arm about the pivot axis, movement of the associated row co-ordinate member beyond an extent at which said stop means is engaged by said arm being arranged to cause displacement of the pivot axis against said spring bias.

6. A crossbar switch in accordance with claim 1 wherein each contact set includes an operating comb member with which the associated interposer member engages on operation of that contact set, and operation of the associated column co-ordinate member which drives said associated interposer member also drives the remaining interposer members of that column into positions adjacent to but out of engagement with the respective comb members, whereby movement of any of said remaining interposer members of the column by movement of their respective row co-ordinate members is obstructed, such obstruction being accommodated by the lost motion between the movement of the row co-ordinate member and the resulting movement of the interposer members. 

1. A crossbar switch comprising an array of contact sets arranged in rows and columns, an interposer member and an elongated interposer arm in respect of each contact set, a set of row coordinate members each coupled to the interposer members of a respective row by way of the respective interposer arms, means for operating each row co-ordinate member individually to drive the associated row of interposer members in a direction transverse to the length of the respective interposer arms into respective driving positions, a set of column co-ordinate members each column co-ordinate member being coupled to the interposer members of a respective column, means for operating each column co-ordinate member individually to drive any interposer member of the respective column, which interposer member is in a said driving position, in a direction generally along the length of the respective interposer arm into operative engagement with the associated contact set, the interposer members being slidable along the respective interposer arms, and resilient support means for the interposer arms, said resilient support means providing lost motion coupling between a row co-ordinate member and the associated interposer members whereby the travel of said interposer members may be limited independently of the travel of the row co-ordinate members.
 2. A crossbar switch in accordance with claim 1 wherein each interposer arm is substantially rigid and the associated interposer member is coupled to the arm at or near one end thereof, the arm having a transverse pivot axis at or near the other end of the arm.
 3. A crossbar switch in accordance with claim 2 wherein said resilient support means for the interposer arms comprises respective leaf springs which apply a spring bias to and serve to locate said arms.
 4. A crossbar switch in accordance with claim 2 wherein each row co-ordinate member engages the associated interposer arm at a point intermediate the interposer member and the pivot axis, the arrangement being such that if the movement of the interposer member is limited on operation of the row co-ordinate member the pivot axis is displaced against said spring bias.
 5. A crossbar switch in accordance with claim 2 wherein stop means are provided in the region of the interposer member to limit the pivotal movement of the interposer arm about the pivot axis, movement of the associated row co-ordinate member beyond an extent at which said stop means is engaged by said arm being arranged to cause displacement of the pivot axis against said spring bias.
 6. A crossbar switch in accordance with claim 1 wherein each contact set includes an operating comb member with which the associated interposer member engages on operation of that contact set, and operation of the associated column co-ordinate member which drives said associated interposer member also drives the remaining interposer members of that column into positions adjacent to but out of engagement with the respective comb members, whereby movement of any of said remaining interposer members of the column by movement of their respective row co-ordinate members is obstructed, such obstruction being accommodated by the lost motion between the movement of the row co-ordinate member and the resulting movement of the interposer members. 